4E GitP World-Building: Basic Setting and Themes

[Eerie]

Also, semi-unrelated, but are elves half-human, half-eladrin? And does that make half-elves quarter-eladrin?

Here is another suggestion: setting with realistic biology.

All races are actually one species with a huge dispersion of the gene pool. Hence, everyone can mate with everyone, and no such stupid terms as half-carrot exists. If human mates with a dragonspawn, the child can be any one of the millions of possible combinations.